This research seeks to identify the components of gonococci that are responsible for their ability to cause human disease, to determine how such components function, and to evaluate the mechanisms of human resistance to gonococci. Results during the initial grant period have indicated: (1) that both virulent and avirulent colonial types of gonococci contain similar plasmids and, hence, suggest that the genetic information specifically for virulence is not a part of the plasmids; (2) that virulent gonococci and avirulent organisms of colonial type 3 have an antiphagocytic component (in the case of virulent organisms, in addition to pili, the dominant antiphagocytic structure) that is sensitive to treatment with EDTA; (3) that formation of the EDTA- sensitive antiphagocytic component is inhibited by vancomycin but not by inhibitors of protein synthesis, and (4) that it is possible to label radioactively and study the properties of diverse gonococcal cellular macromolecules. Further studies will involve attempts: (1) to characterize chemically and immunologically the EDTA-sensitive antiphagocytic activity, (2) to evaluate the effect of virulent gonococci on exocytosis of lysosomal substances from leukocytes; and (3) to evaluate the effect in vitro of human tissue extracts on the growth and virulence determinants of gonococci.